This invention relates to a method and apparatus for manipulating large sections of non-rectangular-shaped artificial turf, and more specifically to a method and apparatus facilitating repeated covering and uncovering of a surface with such turf.
Artificial turf installations in recent years have become quite widespread for indoor and outdoor uses. In a typical convertible indoor installation rectangular-shaped sections of artificial turf have been installed to removably cover a support surface in that it is repeatedly rolled up and stored after each use so the area underneath can be used for other purposes. For example, such a convertible system has been used in manually covering a basketball floor with synthetic turf where it is used for football practice and then manually rolled up and stored nearby in large rolls to expose the floor for use in playing basketball. Aside from the need for extensive manpower to roll out and roll up the large sections of artificial turf, the drawback to this approach is the lack of an effective way to manipulate the large artificial turf area to remove wrinkles which develop during the roll up and roll out phases.
A significant improvement is disclosed in U.S. Pat. No. 4,399 954, incorporated herein by reference, which discloses the manipulation of large sections of artificial turf supported on a pneumatic cushion. To cover a field the artificial turf is pulled from a roll of artificial turf supported along its length by support rollers. For instance, an entire football field can be pulled from the roll because friction between the artificial turf and the support surface is minimized with a pneumatic cushion, provided by a blower feeding low pressure air to a few ports in a row adjacent the roll, which is often below grade. When the field is extended the blower is shut down allowing the artificial turf to settle onto the support surface. The artificial turf can be rapidly removed by applying a pneumatic cushion then winding the artificial turf onto the roll, for instance by driving the support rollers.
Such a rapid field conversion system has benefited the management of multi-use stadia by allowing the scheduling of events more closely together to maximize facility use. For instance a football game can be played on artificial turf supported over a basketball court on the same day as a basketball game due to the minimal time required for field conversion, often less than one hour.
In this regard FIG. 1 illustrates a plan view of a central portion of a stadium having a football playing field with a rapid conversion apparatus. The central section of the stadium is bounded by a circular circumference 2, within which are seating segments 3 which can move for instance on circular arc tracks. A football playing field 1 of artificial turf can be installed by pulling the turf on a pneumatic cushion provided from ports adjacent a pit 6. The air cushion supported turf can be pulled from a roll stored in the pit 6 by cables 7 attached to a spar 8 at the leading margin of the turf. Winches 9, within the seating segments 3 pull on the cables 7 which are guided by capstans 10 and pulleys 11.
To remove the field, a pneumatic cushion is provided via the ports. With reference to FIG. 2, the turf is wrapped onto a cylindrical core 12 by driving support roller 13. A support roller 14 assists in supporting the roll as its diameter changes. When the artificial turf is removed from the field, a lid 15 can be closed down over the pit 6.
A principal disadvantage of such rapid field conversion systems is that they are not amenable to use in those facilities where non-rectangular-shaped artificial turf is utilized, such as for playing baseball. For purposes of describing this invention a non-rectangular-shaped segment of artificial turf is defined as having a margin which extends at an oblique angle from the edge of the segment which is fastened to an elongated core onto which the artificial turf can be wrapped.
If a non-rectangular-shaped segment of artificial turf were wrapped into a roll, an irregular circumference would result. Artificial turf, for instance comprising a mat of synthetic grass and a resilient polymeric cushion, can have a density in the range from about 0.4-2.0 pounds per square foot (2-10 Kilogram per square meter), for instance about 1.0 pound per square foot (4.9 Kilogram per square meter). Artificial turf for a baseball playing field would often be wrapped in a roll of at least about 400 feet (122 meters) in length and have a mass on the order of magnitude of 100,000 pounds (45,400 Kilograms). Any attempt to wrap such a non-rectangular segment of artificial turf of such large mass onto a cylindrical core of about 400 feet (122 meters) in length would readily result in a bent core incapable of rotation.
By this invention applicant has provided apparatus for rapid field conversion of non-rectangular surfaces of artificial turf, such as for a baseball playing field, with apparatus that will allow for non-deflecting support to the artificial turf-wrapped core.